International Date Line timeline
When the date changed, who recorded it and what the sources establish. This timeline brings together the episodes studied in the atlas; it does not list every Pacific time-zone change.
Calendar decisions, accounts and map editions are identified separately. An approximate date remains approximate even when it appears in a database.
Download the timeline with sources (CSV)
1814-09-17 · Account
Pitcairn
Pipon records a one-day disagreement during his visit on 17 September 1814: the ships kept Saturday, while John Adams believed it was Sunday the 18th.
We consulted a transcription of the account. This passage gives no order to change the calendar and draws no boundary around the island. Our circle is an explanatory symbol.
- Pipon · Narrative, 1814 Últimos párrafos / Final paragraphs
1844-12-31 · Calendar change
Filipinas / Philippines
Clavería’s decree of 16 August 1844 ordered Monday 30 December to be followed by Wednesday 1 January 1845. Benko reproduces the Spanish text.
The reproduction comes from a copy certified in 1889. We have not inspected the 1844 original. IANA assumes the Marianas changed at the same time; this does not establish the full corridor drawn on our map.
- Benko · Das Datum auf den Philippinen, 1890 pp. 13–14
- IANA · Marianas Comentario / Comment Paul Eggert, 2018-11-18
Finales de 1846 / Late 1846 · Date proposed by a study
Tahití / Tahiti
Kape and Koenig place a Tahitian calendar change in late 1846, in their study of a May 1847 letter from Pomare IV. We therefore do not treat 1847 as an established date of change.
This is a 2013 study, not the original order. A search of the official bulletin’s 1842–1850 index did not locate that order. The exact date, affected islands and shape of the detour remain unestablished.
- Jean Kape & Robert Koenig · Bulletin de la Société des Études Océaniennes 329 (2013) p. 104
- Archives de Polynésie française · Bulletin officiel 1842–1850 Índice consultado / Index searched
1867 · Transfer and calendar context
Alaska
The 1867 treaty documents Alaska’s transfer. The Admiralty notes explain how the change of date was reflected in the line near the Bering Strait.
The treaty describes territorial boundaries; it does not establish a worldwide Date Line. A local calendar account must identify the ceremony date, calendar used and place where it was recorded.
- US National Archives · Alaska purchase Tratado de cesión / Treaty of cession
- Hydrographic Department · Notes on the History of the Date or Calendar Line Reimpresión / Reprint 1930 · PDF pp. 4–5
1892-07-04 · Calendar change
Samoa
The proclamation of 16 June 1892 ordered the old calendar’s Tuesday 5 July to be called Monday 4 July. It appeared in the Samoa Times on 18 June, page 3.
The order establishes the calendar instruction. The 2 July newspaper announces celebrations for the second Monday. Neither source fixes every turning point of an oceanic line.
- Samoa Times · Royal Proclamation, 18 June 1892 p. 3 · columna / column 2
- Samoa Times · Local and General News, 2 July 1892 p. 2 · primer párrafo / first paragraph
1899-12-25 · Calendar change
Islas Cook / Cook Islands
The 1899 Christmas Day Act directed that New Zealand’s 25 and 26 December be counted as one date, 25 December, in the Cook Islands. Tuesday the 26th would follow.
The law is reproduced on page 20 of the 1900 parliamentary report. It does not establish that Niue followed the same order. The outline’s 1900 label refers to a map publication, not the date of this law.
- AJHR 1900 · A–3 · Christmas Day Act 1899 p. 20 · No. 10 (1899); contexto / context p. 15
- Hydrographic Department · Notes on the History of the Date or Calendar Line Reimpresión / Reprint 1930 · PDF pp. 4–5
1899 / 1900 / 1910 · Chart editions and revision
Morrell · Byers
The Admiralty notes distinguish the US chart of 1899, the British chart of 1900 and the 1910 revision, reported in 1911. That revision removed the bend around Morrell and Byers, islands no longer shown on its charts.
The text is dated November 1921 and was reprinted in 1930. It supports neither an additional 1919 revision nor the received B03 variant’s “after c. 1924” date. We retain that variant as archive material, not as a civil change.
- Hydrographic Department · Notes on the History of the Date or Calendar Line Reimpresión / Reprint 1930 · PDF pp. 4–5
c. 1969 · Date retained with reservations
Kwajalein
IANA uses 1969 for an earlier Kwajalein change, but its own comment says it retains that date pending better evidence. This is not a verified 1969 government order.
The date remains approximate in this reconstruction. A contemporary order or local record of the change is needed to establish it.
- IANA · Time Zone Database · australasia Pacific/Kwajalein · comentario / comment Paul Eggert, 2022-03-31
1993-08-21 · Calendar change
Kwajalein
The Associated Press report quoted by IANA describes a Friday-to-Sunday jump in August 1993. Its time-zone record skips Saturday 21 August in Kwajalein.
The change concerns Kwajalein. It must not be extended to all the Marshall Islands or used to date the beginning of the earlier arrangement.
- IANA · Time Zone Database · australasia Pacific/Kwajalein · comentario / comment Paul Eggert, 2022-03-31
1994-12-31 / 1995 · Time-zone record; local implementation under study
Kiribati
In 2018, Paul Eggert corrected an IANA data-entry error: the eastern islands had skipped 31 December 1994, not 1 January 1995.
A separate question remains: Hay (2001, p. 32) reproduces a local 4/5 January notice and cites Cabinet Memo No. 36/94, MHARD 5/16. The original notice is needed to establish whether it describes delayed implementation. The IANA error itself is explained.
- Paul Eggert · Pacific/Enderbury & Pacific/Kiritimati, 4 February 2018 Mensaje y parche / Message and patch
- IANA · Pacific/Kanton · Pacific/Kiritimati Transición / Transition 1994 Dec 31
- David E. Hay · The Influence of the International Date Line on the Pacific Sabbath (2001) p. 32 · nota / note 22 · copia del archivo cotejada / archive copy checked
2011-12-30 · Calendar change and legislation
Samoa
Section 5 of the 2011 Act moves the line east of Samoa and specifies 171° west. Its schedule shows the former line in red and the new line in blue. We have checked the image.
The map is on PDF page 5, after the schedule heading on page 4. The Act concerns Samoa; it does not legislate for Tokelau or American Samoa. Our outline remains a simplification.
- Samoa · International Date Line Act 2011 Art. / Section 5 · PDF p. 2
- Samoa · Schedule · mapa / map PDF p. 5 · cotejado visualmente / visually checked
Using this timeline
Each event has its own link. When citing a historical date, also cite its supporting source and retain the stated qualifications. External images and documents retain their own rights and terms of use.